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Insufficient effective prestress in prestressed concrete bridges causes structures premature invalidation. Based on Hertz Contact Theory and Finite Element Method, this paper points out the irrationality of the effective prestress formula in Curving Hole at present, and then explores the distribution law of contact stress in Curving Hole. Several contact stress distributions in Curving Hole are hypothesized and the prestress loss caused by friction was compared with each other. The analysis in this paper is very important for further study of factors affecting effective prestress in Curving Hole, and it plays a remarkable role on the design of long span prestressed concrete bridge.

The Gauss-Newton inversion (GNI), an iterative algorithm, is developed from the frequency domain to the time domain in order to simultaneously reconstruct the electrical permittivity and electric conductivity of a two-dimensional object of interest by directly using the ultra-wideband time-domain measurement data. The resulting forward problem is solved by the finite difference time domain method, while the ill-posedness of the corresponding inverse problem is restrained by an adaptive regularization technique at each iteration. Furthermore, the modified GNI algorithm is applied to four types of numerical examples where a noise model is considered, and the simulated results preliminarily demonstrate its feasibility and robustness. The reconstructed images present super resolution, thus it is expected to be used in the engineering practice such as the detection of the early-stage breast cancer.

The fluid model and the self-consistent dust charging model are used to investigate the Bohm criterion for the plasma sheath including two species of charged dust particles. Numerical calculation results are obtained using quasi-Newton method. Effects of two species of dust particles on the dust charging and the ion Mach number are discussed. As the number density of the fewer dust particles is enhanced, different changes will take place on the surface potential of the two species of dust particles. Either more number density or smaller radius of the fewer dust particle may result in a larger ion Mach number. In addition, the ion Mach number will reduce when the velocity of any kind of dust particles at the sheath edge increases.